The Middle Jurassic is the second epoch of the Jurassic Period . It lasted from about 174.1 to 161.5 million years ago . Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland , the Calcaire de Caen of France , the Daohugou Beds in China, the Itat Formation in Russia , the Tiouraren Formation of Niger , and the Isalo III Formation of western Madagascar .
23-471: The Great Oolite Group is a Middle Jurassic stratigraphic unit that outcrops in southern England. It consists of a complex set of marine deposits primarily mudstone and bioclastic ooidal and fine grained limestone, deposited in nearshore to shelf settings. It is exposed at the surface as a variably thick belt extending roughly NE-SW from the coast of Dorset up to the Humber . It is also present at depth in
46-464: A low, open, shrubby canopy . The large seeds of Ginkgo and its habit of " bolting "—growing to a height of approx. 10 metres (30 feet) before elongating its side branches—may be adaptations to such an environment. Diversity in the genus Ginkgo dropped through the Cretaceous (along with that of ferns, cycads, and cycadeoids) at the same time the flowering plants were on the rise, which supports
69-648: A markedly different (and poorly documented) form persisted in the Southern Hemisphere . At the end of the Pliocene , Ginkgo fossils disappeared from the fossil record everywhere except in a small area of central China, where the modern species survived . It is doubtful whether the Northern Hemisphere fossil species of Ginkgo can be reliably distinguished. Given the slow pace of evolution and morphological similarity between members of
92-581: A species may exist as a contiguous entity for many millions of years, many of the ginkgo's life-history parameters fit. These are: extreme longevity; slow reproduction rate; (in Cenozoic and later times) a wide, apparently contiguous, but steadily contracting distribution , coupled with, as far as can be demonstrated from the fossil record, extreme ecological conservatism (restriction to disturbed streamside environments). Modern-day G. biloba grows best in well-watered and drained environments, and
115-663: A specific stratigraphic formation in the United Kingdom is a stub . You can help Misplaced Pages by expanding it . Middle Jurassic During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana , and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing
138-523: Is found in the wild only in China, but is cultivated around the world. The relationships between ginkgos and other groups of plants are not fully resolved. The ginkgo ( Ginkgo biloba ) is a living fossil , with fossils similar to the modern plant dating back to the Permian , 270 million years ago. The closest living relatives of the clade are the cycads , which share with the extant G. biloba
161-510: Is a sister to a clade composed of conifers and gnetophytes, and that Ginkgo and cycads form a clade within the gymnosperms . A 2013 study examined the reasons for the discrepant results and concluded that the best support was for the monophyly of Ginkgo and cycads. The genus name is a mis‐ transliteration of the Japanese pronunciation gin kyo for the kanji Japanese : 銀杏 , lit. 'silver apricot'. This name
184-534: Is adopted from Chinese, the name being found in Chinese herbology literature such as Daily Use Materia Medica ( 日用本草 ) (1329) and Compendium of Materia Medica ( 本草綱目 ) published in 1578. Despite its spelling, which is due to a complicated etymology including a transcription error, "ginkgo" is usually pronounced / ˈ ɡ ɪ ŋ k oʊ / , which has given rise to the common alternative spelling "gingko". The spelling pronunciation / ˈ ɡ ɪ ŋ k ɡ oʊ /
207-481: Is also documented in some dictionaries. Engelbert Kaempfer first introduced the spelling ginkgo in his book Amoenitatum Exoticarum , taking it from Japanese herbalist Tekisai Nakamura [ ja ] in his manuscript, Kinmō Zu'i [ ja ] , acquired in Dejima between 1689–91. It is considered that he may have misspelled ginkyo or ginkio as ginkgo . This misspelling
230-454: Is also used as the English common name. The order to which the genus belongs, Ginkgoales , first appeared in the Permian , 270 million years ago , and Ginkgo is now the only living genus within the order. The rate of evolution within the genus has been slow, and almost all its species had become extinct by the end of the Pliocene . The sole surviving species, Ginkgo biloba ,
253-580: The Paleo-Tethys Ocean . A subduction zone on the coast of western North America continued to create the Ancestral Rocky Mountains .Significant subduction zones were active along practically all of the continental edges surrounding Pangea, as well as in southern Tibet, southeastern Europe, and other locations, to allow the formation of fresh seabed in the proto-Atlantic Ocean. Plate tectonic activity in subduction zones caused
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#1732775766596276-607: The Weald and Wessex Basins , as well as offshore. Several of the constituent formations, notably the Taynton Limestone Formation and the Forest Marble Formation are notable for their fossil content, including those of dinosaurs and pterosaurs and some of the earliest mammals. This England -related article is a stub . You can help Misplaced Pages by expanding it . This article about
299-528: The Middle Jurassic, (including cetiosaurs , brachiosaurs , megalosaurs and primitive ornithopods ). Descendants of the therapsids , the cynodonts , were still flourishing along with the dinosaurs. These included the tritylodonts and mammals. Mammals remained quite small, but were diverse and numerous in faunas from around the world. Tritylodonts were larger, and also had an almost global distribution. The first crown-group mammals appeared in
322-402: The characteristic of motile sperm. Motile sperm is believed to be a basal trait of green plants , as it is also found in most non- seed plants such as ferns and mosses, as well as green algae, which are believed to be the base of the green plant clade, the group in which the last common ancestor of land plants emerged. Motile sperm have been lost in all seed plants except for the ginkgo and
345-577: The construction of north-south mountain ranges such as the Rocky Mountains and the Andes all along the west coast of North, Central, and South America. The Middle Jurassic is one of the key periods in the history of life on Earth. Many groups, including dinosaurs and mammals , diversified during this time. During this time, marine life (including ammonites and bivalves ) flourished. Ichthyosaurs , although common, are reduced in diversity;
368-416: The cycads, making it a shared conserved trait —a plesiomorphy —and implying these two groups themselves form a clade, sharing a common ancestor also with the trait, which diverged early from the rest of the seed plant lineage. The time of this divergence is estimated to be extremely ancient, dating to the early Carboniferous . Fossils attributable to the genus Ginkgo with reproductive organs similar to
391-485: The extremely similar fossil Ginkgo favoured similar environments. The sediment records at the majority of fossil Ginkgo localities indicate it grew primarily in disturbed environments along streams and levees . Ginkgo therefore presents an " ecological paradox " because, while it possesses some favourable traits for living in disturbed environments ( clonal reproduction ), many of its other life-history traits (slow growth, large seed size, late reproductive maturity) are
414-884: The genus, there may have been only one or two species existing in the Northern Hemisphere through the entirety of the Cenozoic : present-day G. biloba (including G. adiantoides ) and G. gardneri from the Palaeocene of Scotland . At least morphologically, G. gardneri and the Southern Hemisphere species are the only known post-Jurassic taxa that can be unequivocally recognised. The remainder may have been ecotypes or subspecies . The implications would be that G. biloba had occurred over an extremely wide range, had remarkable genetic flexibility and, though evolving genetically, never showed much speciation . While it may seem improbable that
437-425: The late Early Jurassic. A group of cynodonts, the trithelodonts , were becoming rare and eventually became extinct at the end of this epoch. Conifers were dominant in the Middle Jurassic. Other plants , such as ginkgoes , cycads , and ferns were also common. Ginkgo Salisburia Sm. Ginkgo is a genus of non-flowering seed plants , assigned to the gymnosperms . The scientific name
460-675: The modern species first appeared in the Middle Jurassic , and the genus diversified and spread throughout Laurasia during the Jurassic and Early Cretaceous . It declined in diversity as the Cretaceous progressed with the extinction of species such as Ginkgo huolinhensis , and by the Palaeocene , only a few Ginkgo species, Ginkgo cranei and Ginkgo adiantoides , remained in the Northern Hemisphere , while
483-885: The notion that flowering plants, with their better adaptations to disturbance, displaced Ginkgo and its associates over time. Trichopitys heteromorpha from the earliest Permian of France, is one of the earliest fossils ascribed to the Ginkgophyta. It had multiple-forked non-laminar leaves with cylindrical, thread-like ultimate divisions. Sphenobaiera (early Permian–Cretaceous) had wedge-shaped leaves divided into narrow dichotomously- veined lobes, lacking distinct petioles (leaf stalks). Baiera (Triassic–Jurassic) had similar multiple-lobed leaves but with petioles. As of February 2013 , molecular phylogenetic studies have produced at least six different placements of Ginkgo relative to cycads , conifers , gnetophytes and angiosperms . The two most common are that Ginkgo
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#1732775766596506-447: The opposite of those exhibited by "younger", more-recently emerged plant species that thrive in disturbed settings. Given the slow rate of evolution of the genus, it is possible that Ginkgo represents a pre- angiosperm strategy for survival in disturbed streamside environments. Ginkgo evolved in an era before angiosperms (flowering plants), when ferns , cycads , and cycadeoids dominated disturbed streamside environments, forming
529-467: The top marine predators, the pliosaurs , grew to the size of killer whales and larger (e.g. Pliosaurus , Liopleurodon ). Plesiosaurs became common at this time, and metriorhynchids first appeared. In the Jurassic seas, a wide range of animals swam. Cartilaginous and bony fish were plentiful. Large fish and marine reptiles were plentiful. Many of the major groups of dinosaurs emerged during
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